Sound-producing device



Jan. 6, 1931. J. s. HIGH 1,788,105

SOUND PRODUCING 'DEVICE Filed Aug.' 7, 1926 WITNESSES:

'IXIJLM BY 7 ATTRNEY INVENTOR Patented Jan. 6, 1931 unna-nasrarrsf wares..

Parana NSYI'NANIA" nssronor. To" Wns'rnionoosa ELECTRIC@"iitANnA'cfRINGoomanYfn conroniirron on PENNSYLVANIA l desirable which .is 'capable Yof radiating.

equally wellal1 i'the frequencies involved.

lfyPlane diaphragmsv of the usuall type-'have been found unsatisfactory, as .they-.have .a-

moetneed-itendencyt bei accentuate- .-thOSe wassen-@geweven tm-2.11.'.Own-.naturalfrr quencies.' Diaphragms having :large arcas, 15, such as cones, and. the., like, have been used with a. certailr amount o f. suc-cess, but, even vit-h them,rnia ny. :Luidesimble' sounds' are..pro

duced which; ,fare often .causedby inertiareactions between the actuating means and the diaphragm. i 2:. 3

It is an vobject of my invention toprovide a diaphragm ,which gives anpequally good response over.: a .wide range. of g frequencies,

having .no pronounced natural; period of vfits own within the :range .of .f the \.-'h1ch-arc:tofbe reproduced..

Another object of my invent-ioni is .to so :frequencies construct the connection between the actuat.

4a for introducing a correction factor into. the

response curve. j Another and further object is toprovide '.1 new-and improved methodofcemcnting a metallic diaphragm to a supporting element. l attain these objects and others which will be more fully explained later by soconstructinga diaphragm thatit will be responsive, as.

a whole, to movements of the actuating means representing sounds of large ampli-- tude and low frequency and will.. also, re-

.My invention relates to sound-producing I apparatus, and it. has paticularrelation 4t0 suc-happaratus 'Av-herein. f a relativelysmall l rialiuieationfmed Apg'ust '1, 192e. serial No. 427,877.

spond locally to movements representing soundshavingvery high frequencies. y 1

...In orderto obtainv a level response curve,A

I -mayadd to a composite diaphragm, an eleij ment which. controls the output to. the at- 5;,

mospherc .ofthat portion responsive to 'the higher frequcncies.

I .interpose aismbetween the diaphragm. and .the actuati ,g means, n connection which absorbesall radial-components 0f :the move- 6g ment ofthe driving means, thereby preventing such components from setting up' un. desirable dotibio-frequency vibrations in thc, diaphragm. This. connection delivers 'only purely rectilinear Amovements to the diae5 phragm. I am tlmsenabled to provide a, vibrating system which, as awhole, is evenly.i

responsiveto the entire band of frequencies.

involved in speechr and music.

In ordervthat-A my invention may be more fuily understood, reference is 110W made to the accompanying drawings and to the 'fob lowing description. f

.Fig. l. is an elevational vie.v,partlywin section, of a preferred lform of my invention, in which the actuating meansisindicated diagrammatically.

Fig. 2 is a view, in'perspective, of a modilied form of connection between theactuating means and the diaphragm.

Fig. 3 is an elevational View, partly insection, of a modified form of connection.

Fig. 4 is asectional .view taken alongthe. line .IV-IV .of Fig. 3.

Fig. 5 is a view of a portion of the cover s; plate of 'he diaphragm, showing modificationp.l y p.

As illustrated in F ig. l, a diaphragm 1 is mounted for vibration in a housing 2 and is operatively connected to an electromagnetic on actuating means comprising a balanced armature 3 suspended between the pole .piece NN and SS of a. permanent-magnet system by means of a torsion spring 4. The dinphragm comprises a portion 'which is trump- S et-shaped in cross section and which is preferably spun or stamped from a. very light metal, such as aluminum. Y For bestresultsT this portion of the diaphragm should have a wall of such shape as Would be given by the 1:9

rotation around an axis of an exponential curve lying in the plane of said axis. The lower flaring portion of the trumpet-shaped element 5 is flattened out into an annular mounting rim 7 provided with a plurality of perforations therethrugm g 1 The upper orslnafliendmf t'le""p1tion is closed by a wall 9 pierced by a mounting hole throughivhich.projects a clamping Abolt 10 p r'ovided-i iiytlina. boived. washer'V II and a'. lockift iostincaroaiid the'daimpnig bolt l0 is a cushion of resilient;materi al13, the whole assembly of cushion and clamping holt passing through an openingrifn the arma?.

is' flattened into an: annulus 17 correspond" ingto'th'e mounting rim of element 5, which annulus 17 is provided with a plurality of perforations 1Q.

Athin annulus 19 of high-grade rubber, or similar material, lea'ther, fabric orthe like. is positioned between the perforatcdflangcs 7 anll''and lield in lacefbyfiilier c'clii'ent or moisture-proof g ue.` `Overlying each flange may be placed rings'20 which will be firmly united thereto by the cement exuding through the perforations 8 and 18. This type of connection is somewhat analogous to riveting, and is extremely firm and durable.

The aniinlus 19 is secured between the elements Qlfand 22' wh'ic-lrar'e united together by screws 23 to Vf ')r'rn a diphrafrin chamber having an outlet 24 to the atmosp'- re.l

The diaphragm assembly I have thus far described I' term a. pseudo-plunger, by that designati-on n'ieanmg audiaphragniall parts of which do not move in strict unison when subjected to a driving force applied at the small end of the trumpet-shaped element. Driving forces having lon7V frequency and large amplitude are transmitted by the rigidity of the element- 5 to the assenihtv :is a whole. On the other hand, forces having a very high frequency tend to cause the elei nient 5to vibrate loeallynd to emphasize the resonant frequency of the chamber defined by the element-s 5 and l5 of Vthe diaphragm. l

In order to take advantage 'ifi the fact that thc portion 5 of the diaphragm tends to vibrate locally ihre-'spense to high frequencies, the cover plate 15'isprevided with an opening 16 ora series of openings v'vliich I contemplate making variable in s'i'Zc' by :idjustab'le means`,or by' means of plugs of niterial, such as felt,.cotton orltlie like'. W'he'n the opening 16 is relatively unobstructed, it is apparent: that the higher frequencies generated in tinl element 5 have a free passage to the outside air by '.vay of the sound opening :24.

The chamber defined by the interioin-'al'ls of the element 5 and the cover plate 15 will usually he resonant to some one frequency and this characteristic of resonance is also of .importance when the response curve is'to be modified.

By providing the opening 16, or a series of' openings, in the cover 15, I anx enabled to fluidity4 the' efiect.- of' .the enclosed rcsonznicc chamber on `the output of' the device. lf the response curve poor for the higher frcqncncies', thi'fsi',Ax openings -niayifalaige'a'nd unobstructed il" 'the cum-"c sirow's a preponderance of thc` higher frequencies. these holes ma y bc closed or may be provided with adaniping' naterial.

The cover plate 15, while desirable as an adjunct to shall dial'ihragins of the type used l in pln'mograp'hs, or in loud-speakers proi-ided vrith horns. is not essential with large' diaphragme of the type that are freely exposed on both sides to unconfined air when in use. I have found that large diaphragm-s having an vexponential curvature, instead of being made conical as is customary, give a snflicien'tly evenresponse to plurality of different actuating frequencies without the necessity'of resorting to the modifying cover plate. 1

By reasoitof the resilient mounting 13, radial components of the movements o'f the a rmature 3far`e, toa large extent. absorbed and damped out before reaching the diaphragm. This is decidedly advantageous, as such movements tend to set up parasitic vibrations in the diaphragm which manifest themselves as hissing or other unpleasant sounds in the output. l

By concentrating the restoring force in the spring 4, and by mounting the diaphragm so that transverse strains fire net transmitted thereto, the quality of the output is greatly improved.

In Fig. 2 I have illustrated a modified form of connector for use between the driving means and thc diaphragm. IVhcn this type of connector is employed. the upper portion 5r of the diaphragm is provided with two oppositely extending ears 25. The armature 3. instead of having an opening therethrough, is provided with concave portions 26. Between the` armature and the ears .25 is placed a resilient cushion 27 and directly below these ears' are other' resilient cushions 28. the cars being held firmly against the lower portion of the armaturev by means of a spring element 29 of C shape which exerts a pressure 'on the upper side of the armature through acusliion 30. This type of connector prevents lending moments noni being transmitted from the armature to the diaph ragni while efiiciently transmitting stresses along the axis of the trumpetshaped portion 5, and is also self-adjusting- In Figs. 3 and 4 is sllown a modified forni of the connector assembly of Fig. 1. A plu rality of cups 31 and 32 having integral central screws 33 and 34 are held together by means of fiexible spring elements 35 and 3G which are soldered into slots in eac-h cup, as illustrated.

The space between the cups 31 and 32 is occupied by a resilient cushion 37 of rubber or analogous material under a slight amount of pressure. The screw 33 projects through an opening in the diaphragm and is held in position by a locknut 3S, While the opposite screw 34 projects through an opening in the armature 3 and is locked in place by means of a nut 39. The connecting springs 35 and 36, because of th'eir flexibility, permit slight angular movements of the armature 3 with reference to the diaphragm 5. Such movements are. however, damped by the resilient cushion 37 and do not set up vibrator-y motions in the diaphragm. Direct thrusts along the line IV-IV are transmitted by the springs 35 and 36, which are relatively stiff along their longitudinal axes.

A sound reproducer constructed according to my invention has a remarkably even response, none of the frequencies commonly present in speech and music being unduly accentuated.

In addition, my device is quite free from thc. parasitic hissing sounds which mar the output from loud speakers provided with plane diaphragms, or large diaphragms of the cone type.

Although I have illustrated and described certain specific forms of my invention, obvious modications will suggest themselves to others skilled in the art. hfy in veution is accordingly not to be limited except. insofar as is necessitated by the prior art, or by the following claims.

I claim as my invention:

l. In a sound-producing device, a diaphragm comprising a plurality of elements .separated 'uy a continuous annular resilient cushion.

L. ln :i souiul-producing device. a diaphragm comprising a plurality of elements separated by continuous annular resilient means. the diaphragm elements defining a partially closed chamber.

3. In a sound-producing device. a con posite diaphragm comprising a section rosponsive mainly to low frequencies only and a .section responsive in substantial degree to beth low and high frequencies.

4. In a .sound-producing device, a composite diaphragm comprising a plurality of elements, cushioning means between said elelments, onefof'saidv elements having walls cu-rved exponentially.

5."Ina"soundproducing device, a coinposite diaphragm comprising 'a plurality of elements in juxtaposition, the' inner walls of said elements definingl a resonance chamber, andfmeans fvsrhereby' the properties .of said chamberfn'iayfbe utilized to modify the sound produced by said device. v

-fG-In .a sound-producing device, ^a= composite diaphragm comprising elementsdefining a`-^resonanceA chamber, an -openingin a wall of said chamber, and means for adjusting thefchaacteristicszof said opening.

t'i'.xIn'ta sound-producing'device, a eom positefdiapliragm comprising elements defining fa resonance=.cl1aml'ier and means for modifying the resonance .characteristics of said chamber.I :f 1^. ,f

8. InL aJsound-producing device, a composite diaphragm comprising elements defining' a resonance chamber. means forv modifying` the characteristics; ofzsaid chamber, and means having a lownatural period for mounting said diaphragm vin a support.

9.'Inv a`.soundprodueing. device, a compositefdiaphragm comprising elements defining a resonancelchamber, means for modi,- ying the characteristics of said chamber, means A-having .a /lownatural-- period for mounting said.' diaphragm in a support, and means for drivin said diaphragm.

10. Ina-soun p`rodueingvfdevice, a composite 1 diaphragm constituting a pseudoplunger. 'fwa 11.1-In-:a.sound-producing device, a diaphragm comprising elements defining a semiclosed chamber, drivingmeans -coupled to said diaphragm by a resilient coupling and flexible means for mounting said diaphragm in a support. Y

12. In a soundfproducing device, a diaphragm comprising elements defining a semiclosed chamber, one wall of said chamber' having a convex Across-section and another wall of said chamber having a concave cross section :when viewed from the interior 'of said chamber.

13.v Ina sound-producing device, a diaphragm *comprising elements defining a chamber, the walls of one portion of said chamber havingia shape'such as would be given Abythe .rotation around an axis of an exponential curvelying in the plane of said axis.

14. In a sound-producing device, a diaphragni comprising a Wall of such shape as would be given by the rotation around an axis of an exponential curve, driving means, and means for attaching said driving means to said element so that the driving force is applied thereto only along said axis.

15. In a sound-producing device, a diaphragm comprising an element having a wall of such shape as would be given by the rotation aroun'd -an axis ofang' exponential curve, actuating means so associatednvitlr sai'd element that force. is; transmitted; .thereto .along said axis, an elementhaving; lowfrestoring force for mountirigfsaidfdiaphragm, where-.

by high-frequency' vibra-'tions will -set 4up4 waves? in said element while low-frequencyvibrations will tend tofmve saidA diaphragm as a Whole. "f: 3 16. In a soundfproducing' device, av diaphragm 'comprising 'a plurality of imperfor ate metallic elements associated -lviyvresilient cushioning' means. n V- 17. In .a sound-'producing device, .a-:com-

posite diaphragm comprising a trumpetshaped portinflaring outwardly vintofanannulusy provided with zi/plurality of openi ings therethrough, a secondpoi'tlonhaving. an annular peripheral part having a; complez mentai'y relation-.tothe'firstffmentioned annulus and also being fprovided with openings, andv mountingmeans between'said portions.

18. In -a sound-producingdevicegafooxn-A posite. diaphragm? icomprising sa' trmpet' l .shaped portion'flaring outwardly `iiito ananf nulus provided witha; Iplurality of openings therethrough, asecondfportion-'having an annular peripheral par't: ihalvingi a complemen;

ta ry relation to 'the'ffirst mentioned :annul'us'l f and alsobeingprovided With lopen-ings, andf mounting .means cemented; between said1por-1 tions, l:. lfm 44.' -rz-f 1'9. Ina sound-producingffdevioe a Adiaphragm comprising fa trumpeteshaped section: flaringr outwardly into a rim adaptedfjto' he affixed to mountingimeans,andfafeoxer for said Haring portion having al? frestriotable openingtherethrough.

20.**Inarsoundiroducingfdevice, a diaphragm lconmrising a plurality' of .sections in juxtalvmsition, a plurality ofregistering' openings through opposite sections fof .said

diaphragm,v mounting means fbetween: said' .sect-ions, and cementing means for holdingmeans together.

21.*Ina diaphragml adapted to be used in said diaphragm sections'and saidmounting sound-producing devices, a ortion sofsliaped' that it will yield under ine'r ia stresses and -a portion united theretfopat the point'where said yielding is greatest.

In testimonywhereof, I haVe' hereunto sub-` scribed my name this'28th day of July, 1926. JURJENS. HIGH.

analog; 

